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Which gas was least abundant in Earthʹ s early atmosphere, prior to 2 billion years ago?
In their laboratory simulations of the early Earth, Miller and Urey observed the abiotic
A) amino acids.
B) complex organic polymers.
E) genetic systems.
Which of the factors below weaken the hypothesis of abiotic synthesis of organic monomers in early Earthʹs atmosphere?
1. the relatively short time between intense meteor bombardment and appearance of the first life forms
2. the lack of experimental evidence that organic monomers can form by abiotic synthesis
3. uncertainty about which gases comprised early Earthʹ s atmosphere
A) 1 B) 2 C) 3 D) 1 and 3 E) 2 and 3
Which of the following has not yet been synthesized in laboratory experiments studying
the origin of life?
B) liposomes with selectively permeable membranes
C) oligopeptides and other oligomers
D) protobionts that use DNA to program protein synthesis
E) amino acids
In what way were conditions on the early Earth of more than 3 billion years ago different from those on todayʹ s Earth? A) Only early Earth had water vapor in its atmosphere.
B) Only early Earth was intensely bombarded by large space debris C) Only early Earth had an oxidizing atmosphere. D) Less ultraviolet radiation penetrated Earthʹ s early atmosphere.
E) Earthʹ s early atmosphere had significant quantities of ozone.
What is true of the amino acids that might have been delivered to Earth within carbonaceous chondrites?
A) They had the same proportion of L and D isomers as Earth does today.
B) The proportion of the amino acids was similar to those produced in the Miller- Urey
C) There were fewer kinds of amino acids on the chondrites than are found in living organisms today.
D) They were delivered in the form of polypeptides
Which of the following is the correct sequence of these events in the origin of life?
I. formation of protobionts
II. synthesis of organic monomers
III. synthesis of organic polymers
IV. formation of DNA- based genetic systems
Which is a defining characteristic that all protobionts had in common?
A) the ability to synthesize enzymes
B) a surrounding membrane or membrane- like structure
C) RNA genes
D) a nucleus
E) the ability to replicate RNA
Although absolute distinctions between the ʺ most evolvedʺ protobiont and the first living
cell are unclear, biologists generally agree that one major difference is that the typical
protobiont could not
A) possess a selectively permeable membrane boundary.
B) perform osmosis.
C) grow in size.
D) perform controlled, precise reproduction.
E) absorb compounds from the external environment.
The first genes on Earth were probably
A) DNA produced by reverse transcriptase from abiotically produced RNA.
B) DNA molecules whose information was transcribed to RNA and later translated in
C) auto- catalytic RNA molecules.
D) RNA produced by autocatalytic, proteinaceous enzymes.
E) oligopeptides located within protobionts.
RNA molecules can both carry genetic information and be catalytic. This supports the
A) RNA was the first hereditary information.
B) protobionts had an RNA membrane.
C) RNA could make energy.
D) free nucleotides would not have been necessary ingredients in the synthesis of new
E) RNA is a polymer of amino acids.
What probably accounts for the switch to DNA- based genetic systems during the evolution of life on Earth?
A) DNA is chemically more stable and replicates with fewer errors (mutations) than RNA.
B) Only DNA can replicate during cell division.
C) RNA is too involved with translation of proteins and cannot provide multiple
D) DNA forms the rod- shaped chromosomes necessary for cell division.
E) Replication of RNA occurs too slowly.
The synthesis of new DNA requires the prior existence of oligonucleotides to serve as
primers. On Earth, these primers are small RNA molecules. This latter observation is
evidence in support of the hypothesized existence of
A) a snowball Earth.
B) earlier genetic systems than those based on DNA.
C) the abiotic synthesis of organic monomers.
D) the delivery of organic matter to Earth by meteors and comets.
E) the endosymbiotic origin of mitochondria and chloroplasts.
Several scientific laboratories across the globe are involved in research concerning the origin of life on Earth. Which of these questions is currently the most problematic and would have the greatest impact on our understanding if we were able to answer it?
A) How can amino acids, simple sugars, and nucleotides be synthesized abiotically?
B) How can RNA molecules catalyze reactions?
C) How did RNA sequences come to carry the code for amino acid sequences?
D) How could polymers involving lipids and/or proteins form membranes in aqueous
E) How can RNA molecules act as templates for the synthesis of complementary RNA
If natural selection in a particular environment favored genetic systems that permitted the
production of daughter ʺ cellsʺ that were genetically dissimilar from the mother ʺ cells,ʺ then
one should expect selection for
I. polynucleotide polymerase with low mismatch error rates.
II. polynucleotide polymerases without proofreading capability.
III. batteries of efficient polynucleotide repair enzymes.
IV. polynucleotide polymerases with proofreading capability.
V. polynucleotide polymerases with high mismatch error rates.
If relatively small carbonaceous chondrites from space were a significant source of Earthʹ s original amino acids, then which two of these would have been most important in permitting their organic materials to survive impact with Earth?
I. Carbonaceous chondrites must contain no D- amino acids.
II. Earthʹ s early atmosphere must have had little free oxygen.
III. The chondrites must have arrived on Earth before 4.2 billion years ago.
IV. Earthʹ s early atmosphere must have been dense enough to dramatically slow the chondrites before they impacted.
V. The chondrites must have impacted land, rather than a large body of water.
If the half- life of carbon- 14 is about 5,730 years, then a fossil that has one- sixteenth the
normal proportion of carbon- 14 to carbon- 12 should be about how many years old?
Which measurement would help determine absolute dates by radiometric means?
A) the accumulation of the daughter isotope
B) the loss of parent isotopes
C) the loss of daughter isotopes
D) all three of these
E) only A and B
How many half- lives should have elapsed if 6.25% of the parent isotope remains in a fossil
at the time of analysis?
Approximately how far back in time does the fossil record extend?
A) 6,000 years
B) 3,500,000 years
C) 6,000,000 years
D) 3,500,000,000 years
E) 5,000,000,000,000 years
What is true of the fossil record of mammalian origins?
A) It is a good example of punctuated equilibrium.
B) It shows that mammals and birds evolved from the same kind of dinosaur.
C) It includes transitional forms with progressively specialized teeth.
D) It indicates that mammals and dinosaurs did not overlap in geologic time.
E) It includes a series that shows the gradual change of scales into fur.
If a fossil is encased in a stratum of sedimentary rock without any strata of igneous rock
A) easy to determine the absolute age of the fossil, because the radioisotopes in the sediments will not have been ʺ resetʺ by the heat of the igneous rocks.
B) easy to determine the absolute age of the fossil, because the igneous rocks will not have physically obstructed the deposition of sediment of a single age next to the fossil.
C) difficult to determine the absolute age of the fossil, because the ʺ marker fossilsʺ common to igneous rock will be absent.
D) difficult to determine the absolute age of the fossil, because radiometric dating of sedimentary rock is less accurate than that of igneous rock.
Letʹ s say that a hypothetical submersible robot was used to collect samples of sedimentary rock from the sea floor along the section illustrated. The robot moved back and forth along the transect, collecting first from site A, then site III, then site B, then site II, and lastly site D. Assuming that sedimentation has occurred at a constant rate along the transect over the past million years, rearrange the sites mentioned above on the basis of the thickness of the sediments overlying the igneous rock, from thickest to thinnest.
A) A, B, II, D, III
B) I, II, III
C) III, II, D, B, A
D) III, A, II, B, D
E) III, D, II, B, A
An early consequence of the release of oxygen gas by plant and bacterial photosynthesis
A) make life on land difficult for aerobic organisms.
B) change the atmosphere from oxidizing to reducing.
C) make it easier to maintain reduced molecules.
D) cause iron in ocean water and terrestrial rocks to rust (oxidize).
E) prevent the formation of an ozone layer.
Arrange these events from earliest to most recent.
1. emission of lava in what is now Siberia at time of Permian extinctions
2. emission of lava that solidified at the same time as iron- bearing terrestrial rocks began
3. emission of lava that solidified at the same time as rusted iron precipitated from
4. emission of lava in what is now India at time of Cretaceous extinctions
Which free- living cells were the earliest contributors to the formation of Earthʹ s oxidizing
Which of the following statements provides the strongest evidence that prokaryotes
evolved before eukaryotes?
A) the primitive structure of plants
B) meteorites that have struck Earth
C) abiotic laboratory experiments that produced liposomes
D) Liposomes closely resemble prokaryotic cells.
E) The oldest fossilized cells resemble prokaryotes.
What is thought to be the correct sequence of these events, from earliest to most recent, in
the evolution of life on Earth?
1. origin of mitochondria
2. origin of multicellular eukaryotes
3. origin of chloroplasts
4. origin of cyanobacteria
5. origin of fungal- plant symbioses
If it were possible to conduct sophisticated microscopic and chemical analyses of
microfossils found in 3.2- billion- year- old stromatolites, then within such microfossils, one
should be surprised to observe evidence of:
I. double- stranded DNA
II. a nuclear envelope
III. a nucleoid
IV. a nucleolus
V. nucleic acids
Recent evidence indicates that the first major diversification of multicellular eukaryotes
may have coincided in time with the
A) origin of prokaryotes.
B) switch to an oxidizing atmosphere.
C) melting that ended the ʺ snowball Earthʺ period.
D) origin of multicellular organisms.
E) massive eruptions of deep- sea vents.
Which of these observations fails to support the endosymbiotic theory for the origin of eukaryotic cells?
A) the existence of structural and molecular differences between the plasma membranes
of prokaryotes and the internal membranes of mitochondria and chloroplasts
B) the existence of size differences between the cytosolic ribosomes of eukaryotes and the ribosomes within mitochondria and chloroplasts
C) the existence of size differences between some prokaryotic cells and mitochondria
D) the existence of rRNA sequence differences between the cytosolic ribosomes of eukaryotes and the ribosomes within mitochondria and chloroplasts
Which event is nearest in time to the end of the period known as snowball Earth?
A) oxygenation of Earthʹ s seas and atmosphere
B) evolution of mitochondria
C) Cambrian explosion
D) evolution of true multicellularity
E) Permian extinction
The snowball Earth hypothesis provides a possible explanation for the
A) diversification of animals during the late Proterozoic.
B) oxygenation of Earthʹ s seas and atmosphere.
C) colonization of land by plants and fungi.
D) origin of O2- releasing photosynthesis.
E) existence of prokaryotes around hydrothermal vents on the ocean floor.
If two continental land masses converge and are united, then the collision should cause
A) a net loss of intertidal zone and coastal habitat.
B) the extinction of any species adapted to intertidal and coastal habitats.
C) an overall decrease in the surface area located in the continental interior.
D) a decrease in climatic extremes in the interior of the new super- continent.
E) the maintenance of the previously existing ocean currents and wind patterns.
A major evolutionary episode that corresponds in time most closely with the formation of
Pangaea was the
A) origin of humans.
B) Cambrian explosion.
C) Permian extinctions.
D) Pleistocene ice ages.
E) Cretaceous extinctions.
On the basis of their morphologies, how might Linnaeus have classified the Hawaiian
A) He would have placed them all in the same species.
B) He would have classified them the same way that modern botanists do.
C) He would have placed them in more species than modern botanists do.
D) He would have used evolutionary relatedness as the primary criterion for their
E) Both B and D are correct.
The dicynodonts that survived the Permian extinction would initially have had to endure
(or escape from) the physical effects of __________, and subsequently, the biological effects
A) warm temperatures, decreased metabolism
B) arid conditions, disease
C) meteorite shock waves, lack of food
D) increased sea level, lack of freshwater
E) volcanic ash in the atmosphere, increased predation
If an increase in dicynodont species diversity (i.e., number of species) occurred soon after the Permian extinction, and if it occurred for the same general reason usually given for the increase in mammalian diversity following the Cretaceous extinction, then it should be attributed to
A) an innovation among the dicynodonts that allowed them to fill brand new niches.
B) the availability of previously occupied niches.
C) the extinction of the dinosaurs (except the birds).
D) the evolution of humans.
An organism has a relatively large number of Hox genes in its genome. Which of the following is not true of this organism?
A) It evolved from evolutionary ancestors that had fewer Hox genes.
B) It must have multiple paired appendages along the length of its body.
C) It has the genetic potential to have a relatively complex anatomy.
D) At least some of its Hox genes owe their existence to gene duplication events.
E) Its Hox genes cooperated to produce the positional patterns of this organism as it developed.
Bagworm moth caterpillars feed on evergreens and carry a silken case or bag around with them in which they eventually pupate. Adult female bagworm moths are larval in appearance; they lack the wings and other structures of the adult male and instead retain
the appearance of a caterpillar even though they are sexually mature and can lay eggs within the bag. This is a good example of
A) allometric growth.
C) sympatric speciation.
D) adaptive radiation.
E) changes in homeotic genes.
As rat pups mature, the growth of their snouts and tails outpaces growth of the rest of their bodies, producing the appearance of sexually mature males. It is found that sexually mature female rats prefer to mate with mutant, sexually mature males that possess snouts and tails with juvenile proportions. Which of the following terms is (are) appropriately
applied to this situation?
A) sexual selection
C) allometric growth
D) B and C only
E) A, B, and C
A hypothetical mutation in a squirrel population produces organisms with eight legs rather than four. Further, these mutant squirrels survive, successfully invade new habitats, and eventually give rise to a new species. The initial event, giving rise to extra legs, would be a good example of
A) punctuated equilibrium.
B) species selection.
C) habitat selection.
D) changes in homeotic genes.
The loss of ventral spines by modern freshwater sticklebacks is due to natural selection
operating on the phenotypic affects of Pitx1 gene
A) duplication (gain in number).
B) elimination (loss).
C) mutation (change).
D) silencing (loss of expression).
E) up- regulation (increase in expression).
The existence of the phenomenon of exaptation is most closely associated with which of the
following reasons that natural selection cannot fashion perfect organisms?
A) Natural selection and sexual selection can work at cross- purposes to each other.
B) Evolution is limited by historical constraints.
C) Adaptations are often compromises.
D) Chance events affect the evolutionary history of populations in environments that can
If the complex protein assemblage of the prokaryotic flagellum arose by the same general
processes as those of the complex eyes of mollusks (such as squids and octopi), then
A) natural selection cannot account for the rise of the prokaryotic flagellum.
B) ancestral versions of this protein assemblage were either less functional, or had
different functions, than modern prokaryotic flagella.
C) scientists should accept the conclusion that neither eyes nor flagella could have arisen
D) we can conclude that both of these structures must have arisen through the direct
action of an ʺ intelligent designer.ʺ
If the prokaryotic flagellum developed from assemblages of proteins that originally were
not involved with cell motility but with some other function instead, then the modern
prokaryotic flagellum is a(n)
A) vestigial organ.
D) homogeneous organ.
E) allometric organ
In certain motile prokaryotes, dozens of different proteins comprise the motor that powers the prokaryotic flagellum. The motor has a complicated structure, and its various proteins interact to carry out its function. Based on Darwinʹ s explanation for the existence of human eyes, how would he probably have explained the existence of such motors?
A) Because he could not have explained their existence, he would have used supernatural agents as a temporary explanation until the gap in scientific knowledge had been filled.
B) Because he could not have explained their existence, he would have concluded that the human brain has not (and probably cannot) evolve the capability to solve such complex problems.
C) He would have proposed that these motors were the products of aliens, and had been delivered to Earth by extraterrestrial visitors.
D) He would have proposed that less complicated, but still functional, versions (maybe even with a different function) had existed in ancestral prokaryotes.
It has been found that certain proteins of the complex motor that drives bacterial flagella
are modified versions of proteins that had previously belonged to plasma membrane
pumps. This is evidence in support of the claim that
A) some structures are so complex that natural selection cannot, and will not, explain
B) the power of natural selection allows it to act in an almost predictive fashion,
producing organs that will be needed in future environments.
C) the motors of bacterial flagella were originally synthesized abiotically.
D) natural selection can produce new structures by cobbling together parts of other
E) bacteria that possess flagella must have lost the ability to pump certain chemicals
across their plasma membranes.
An explanation for the evolution of insect wings suggests that wings began as lateral extensions of the body that were used as heat dissipaters for thermoregulation. When they had become sufficiently large, these extensions became useful for gliding through the air, and selection later refined them as flight- producing wings. If this hypothesis is correct,
insect wings could best be described as
D) isolating mechanisms.
E) examples of natural selectionʹ s predictive ability.
If one organ is an exaptation of another organ, then what must be true of these two organs?
A) They are both vestigial organs.
B) They are homologous organs.
C) They are undergoing convergent evolution.
D) They are found together in the same hybrid species.
E) They have the same function.
Many species of snakes lay eggs, but in the forests of northern Minnesota where growing
seasons are short, only live- bearing snake species are present. This trend toward species
that perform live birth is an example of
A) natural selection.
B) sexual selection.
C) species selection.
D) goal direction in evolution.
E) directed selection
In the 5—7 million years that the hominid lineage has been diverging from its common ancestor with the great apes, dozens of hominid species have arisen, often with several species coexisting in time and space. As recently as 30,000 years ago, Homo sapiens coexisted with Homo neanderthalensis . Both species had large brains and advanced intellects. The fact
that these traits were common to both species is most easily explained by which of the
A) species selection
C) sexual selection
D) A and B only
E) A, B, and C
The existence of evolutionary trends, such as increasing body sizes among horse species, is
A) a larger volume- to- surface area ratio is beneficial to all mammals.
B) an unseen guiding force is at work.
C) evolution always tends toward increased complexity or increased size.
D) in particular environments, similar adaptations can be beneficial in more than one species.
E) evolution generally progresses toward some predetermined goal.
Fossil evidence indicates that several kinds of flightless dinosaurs possessed feathers. If some of these feather- bearing dinosaurs incubated clutches of eggs in carefully constructed nests, this might be evidence supporting the claim that
A) dinosaurs were as fully endothermal (warm- blooded) as modern birds and mammals.
B) their feathers originally served as insulation, and only later became flight surfaces.
C) the earliest reptiles could fly, and the feathers of flightless dinosaurs were vestigial flight surfaces.
D) the feathers were plucked from the bodies of other adults to provide nest- building materials.
E) all fossils with feathers are actually some kind of bird.
A) all date from 2.7 billion years ago.
B) formed around deep- sea vents.
C) resemble structures formed by bacterial communities that are found today in some warm, shallow, salty bays.
D) provide evidence that plants moved onto land in the company of fungi around 500 million years ago.
E) contain the first undisputed fossils of eukaryotes and date from 2.1 billion years ago.
The oxygen revolution changed Earthʹ s environment dramatically. Which of the following adaptations took advantage of the presence of free oxygen in the oceans and atmosphere?
A) the evolution of cellular respiration, which used oxygen to help harvest energy from organic molecules
B) the persistence of some animal groups in anaerobic habitats
C) the evolution of photosynthetic pigments that protected early algae from the corrosive effects of oxygen
D) the evolution of chloroplasts after early protists incorporated photosynthetic cyanobacteria
E) the evolution of multicellular eukaryotic colonies from communities of prokaryotes
Select the factor most likely to have caused the animals and plants of India to differ greatly
from species in nearby Southeast Asia.
A) The species have become separated by convergent evolution.
B) The climates of the two regions are similar.
C) India is in the process of separating from the rest of Asia.
D) Life in India was wiped out by ancient volcanic eruptions.
E) India was a separate continent until 55 million years ago.
Adaptive radiations can be a direct consequence of four of the following five factors. Select
A) vacant ecological niches
B) genetic drift
C) colonization of an isolated region that contains suitable habitat and few competitor
D) evolutionary innovation
E) an adaptive radiation in a group of organisms (such as plants) that another group
uses as food
A genetic change that caused a certain Hox gene to be expressed along the tip of a
vertebrate limb bud instead of farther back helped to make possible the evolution of the
tetrapod limb. This type of change is illustrative of
A) the influence of environment on development.
C) a change in a developmental gene or in its regulation that altered the spatial
organization of body parts.
E) gene duplication.
Which of the following steps has not yet been accomplished by scientists studying the
origin of life?
A) synthesis of small RNA polymers by ribozymes
B) abiotic synthesis of polypeptides
C) formation of molecular aggregates with selectively permeable membranes
D) formation of protobionts that use DNA to direct the polymerization of amino acids
E) abiotic synthesis of organic molecules
A swim bladder is a gas- filled sac that helps fish maintain buoyancy. The evolution of the
swim bladder from lungs of an ancestral fish is an example of
A) an evolutionary trend.
D) adaptive radiation.
E) changes in the Hox gene expression.
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